In the construction trades and in related fields, it is a constant requirement to position studs, posts, walls, partitions, beams, bolts and a variety of other building materials at predetermined and accurate distances from each other and in a straight line or coplanar to each other. In residential and commercial construction all wall studs, door joists, and roof rafters are placed at exact locations in the structure of the building, and in registration with one another, during construction so as to provide structural support for the building. These structural elements also provide support for interior and exterior surface elements and sheeting materials, such as, drywall, plywood, flooring, exterior siding, insulation, and the like. For example, dry wall is normally screwed or nailed to wall studs so as to form the interior surfaces of a room. Since sheeting materials are manufactured in forty-eight inch widths, the required stud spacing is always a divisor of forty-eight, and is usually sixteen inches to the center of each stud, although occasionally it is twelve, twenty-four, or nineteen and two tenths-inches.
In some instances, the method by which workman precisely locate wall studs, joists, or rafters along walls, the floor or ceiling, or the roof involves extending a tape measure along a portion of the structure so as to find and mark each stud, joist, or rafter location, e.g., at sixteen inch or twelve inch increments along a surface of the structure. Each discrete location is often marked with a pencil, e.g., by an “X,” denoting each appropriate position for a stud to be placed. Finally, a carpenter's square is employed to draw a line perpendicularly through each discrete location to allow for stud alignment. The workman is usually on his or her knees or on a ladder during this process, which adds to its already slow and cumbersome nature.
In another prior art method for laying out regularly spaced structural elements, two separate operations are employed requiring two separate devices. In a first step, a straight line is applied along a surface of the structure using a conventional chalked string or “chalk-line” string. A chalk-line string often consists of a length of chalk-receptive string that is wound upon a spool. The chalk-line string is coated with a red or blue chalk powder directly or, by rubbing the string against a piece of marking chalk, so that chalk particles become entrapped within the porous body of the string. In this way, the chalk-line string may be unwound from the spool and fastened adjacent to a surface of the structure to be marked. The extended chalk-line string is then drawn outwardly, in the manner of a bow string, so that it may be snapped against the surface. As a result, some of the chalk particles are transferred onto the surface thereby creating a straight chalk line marking on the surface that is coincident with the overlying position of the chalk-line string.
The next step employs a measuring device, such as a folding wooden ruler or a flexible, retractable metallic measuring tape. The measuring device is aligned with the chalk line marking and additional, periodic marks are applied manually to the surface to indicate predetermined, accurately-spaced distances along the chalk line marking. In the case of wall studs, such marks generally are spaced from each other by exactly sixteen inches. A workman relies upon the manually-applied marks to indicate, for instance, the relative positions of studs which he erects as a support for a straight wall.
It has been proposed to combine both of these steps by applying over the chalk-line string a number of spaced narrow applications of paint to render the narrow spaced areas non-receptive or non-absorbing to chalk powder. When applied to a surface as previously outlined, such a chalk-line string provides a continuous chalk line marking which is periodically interrupted by narrow voids which are spaced from each other by predetermined distances. The disadvantages of such chalk-line strings are manifold. Firstly, such prior art chalk-line strings do not provide reliably-spaced indicia because the length of a string will vary (i.e., stretch or shrink) to some extent with changes in temperature and humidity; strings increase in length or stretch when under tension, e.g., during snapping, and strings increase in length and become weak after prolonged use. Secondly, such chalk-line strings provide narrowly spaced voids or chalk-free areas which are difficult to locate along the chalk line marking unless they are spaced fairly wide apart, in which case they do not provide an accurate measurement guide. Also, if the chalk line marking is weak in intensity and/or is inadvertently contacted or smeared, voids may appear in unintended areas which can mislead the workman. In other words, a positive mark is more reliable than the absence of a mark. Furthermore, paint or other materials applied to the string surface can wear off, particularly under the effects of repeated transport of the string through the narrow eyelet provided on most prior art devices.
Thus, there is a need for a locator line for reliably, precisely, and repeatably marking the locations on a surface to indicate predetermined, accurately-spaced distances along the line.